This Strategy Note looks at the situation in 2001 – when the EU took the initiative to save the Kyoto Protocol – and now, with a view to assessing the need for, and chances of, invigorated EU leadership in the international effort to combat climate change under the 2015 Paris Agreement. Given the statements made by the Chinese leadership in the aftermath of the recent US elections, it is clear that China is willing to continue playing a leading role, both in its domestic actions and in the international climate negotiations. But, the authors argue, the loss of the developed country partner in the ‘G2’ has put China as a developing country in a difficult position because of the internationally acknowledged requirement for leadership from the developed world. In order to get the maximum ambition out of the Paris Agreement, there needs to be a suitable developed country partner to take up the role of the US in the G2. This, the authors argue, is where the EU can and must enter into the picture: to help provide the geopolitically balanced leadership which the Paris Agreement requires, if not to survive, then in order to be ambitious and effective. They propose two related measures that would be conducive to that end. For the new G2 partnership to be as ambitious and effective as possible, the authors suggest that it should be based on ‘strategic collaborations’, by which they mean collaborative actions that involve some concrete quantified targets to be achieved under the collaboration, be it in terms of reducing (utility) emissions or through the linking of emissions trading schemes. In light of the complexity of competencies in the EU, they also suggest that for collaborations in areas with mixed or sole Member State competence, the presence of a high-level EU ‘Special Envoy for Strategic Climate Change Collaboration’ could be helpful – not only in matters of internal coordination, but as designated interlocutor managing the external relations of the collaborations. Strategic collaborations thus facilitated should help the EU to demonstrate renewed leadership, in particular (but not only) to partner with China in an ambitious and effective new G2. It should also be recognized that strategic relationships with other countries, including G 77, should also be an element in the EU effort.

Estimates of the global economic impacts of observed climate change during the 20th century obtained by applying five impact functions of different integrated assessment models (IAMs) are separated into their main natural and anthropogenic components. The estimates of the costs that can be attributed to natural variability factors and to the anthropogenic intervention with the climate system in general tend to show that: 1) during the first half of the century, the amplitude of the impacts associated with natural variability is considerably larger than that produced by anthropogenic factors and the effects of natural variability fluctuated between being negative and positive. These non-monotonic impacts are mostly determined by the low-frequency variability and the persistence of the climate system; 2) IAMs do not agree on the sign (nor on the magnitude) of the impacts of anthropogenic forcing but indicate that they steadily grew over the first part of the century, rapidly accelerated since the mid 1970’s, and decelerated during the first decade of the 21st century. This deceleration is accentuated by the existence of interaction effects between natural variability and natural and anthropogenic forcing. The economic impacts of anthropogenic forcing range in the tenths of percentage of the world GDP by the end of the 20th century; 3) the impacts of natural forcing are about one order of magnitude lower than those associated with anthropogenic forcing and are dominated by the solar forcing; 4) the interaction effects between natural and anthropogenic factors can importantly modulate how impacts actually occur, at least for moderate increases in external forcing. Human activities became dominant drivers of the estimated economic impacts at the end of the 20th century, producing larger impacts than those of low-frequency natural variability. Some of the uses and limitations of IAMs are discussed.